1. Field of the Invention
The present invention relates to developing devices, image forming apparatuses, image forming systems, sealing members, and methods for manufacturing sealing members.
2. Description of the Related Art
(1) There are known developing devices having, for example, a developer container for containing developer, a developer bearing body for bearing the developer, a charging member for charging the developer bore by the developer bearing body by abutting against the developer bearing body, a supporting member for supporting the charging member, and a sealing member that is for preventing the developer from spilling from the developer container and that is provided in a state in which the side of one end thereof is compressed by the developer container and the charging member and the side of the other end thereof is compressed by the developer container and the supporting member. (See, for example, JP 2001-60038 A.)
In developing devices structured as above, when, for example, the sealing member is compressed evenly and sufficiently across the whole distance from the side of one end to the other in order to appropriately prevent developer from spilling from the developer container, the following problem may arise. Since the compression-repulsion force of the sealing member causes a force to be applied to the supporting member at the side of the other end, this force may cause the supporting member to bend. Bending of the supporting member may cause the charging member supported by the supporting member to bend. Then, due to the bending of the charging member, the pressing force from the charging member to the developer bearing body may become uneven.
(2) Further, there are known image forming apparatuses having, for example, an image bearing body for bearing a latent image, and a developing device for developing the latent image bore by the image bearing body with developer. When these image forming apparatuses receive image signals etc. from an external device such as a host computer, it positions the developing device at a developing position that is in opposition to the image bearing body. The image forming apparatus develops the latent image bore by the image bearing body with the developer contained in the developing device, thus forming a developer image. The image forming apparatus then transfers the developer image onto a medium, thereby forming an image on the medium.
Further, such image forming apparatuses are provided with sealing members for preventing the developer from spilling. (See, for example, JP 2001-60038 A described above.)
Conventionally, urethane foam has often been used as the sealing member for preventing the developer from spilling. With urethane foam, however, the developer cannot be prevented from spilling in some circumstances. That is, since the size of the cells (air pockets) of urethane foam, which is one type of foam, is large and the walls between cells are thick, the developer may pass through the cells and spill from the sealing member if, for example, an unexpected impact is applied to the urethane foam.